USMLE Cardiology

what is the first functional organ in vertebrate embryos?

Heart (beats spontaneously at 4 weeks)

what is caused by a failure of the septum premium and septum secundum to fuse at birth; most are left untreated. Can lead to emboli (venous thromboemboli that enter systemic arterial circulation

Patent Foramen Ovale

what is the most common congenital cardiac abnormality and usually occurs in membranous septum

Ventricular septal defect

Conotruncal abnormalities associated with failure of the neural crest cells to migrate: 3

1. transposition of great vessels

2. Tetralogy of Fallot

3. Persistent truncus arteriosus

Fetal-Postnatal Derivatives: Urachus

Median Umbilical ligament

Fetal-Postnatal Derivatives: Ductus Arteriosus

Ligamentum arteriosum

Fetal-Postnatal Derivatives: Ductus Venosus

Ligamentum Venosum

Fetal-Postnatal Derivatives: Foramen Ovale

Fossa Ovalis

Fetal-Postnatal Derivatives: Notochord

Nucleus Propulsus

Fetal-Postnatal Derivatives: Umbilical Arteries

Medial Umbilical Ligaments

Fetal-Postnatal Derivatives: Umbilical Vein

Ligamentum teres hepatis (in the falciform ligament)

Blood in the umbilical vein has a P02 of_____mmHg and is _____% saturated with oxygen

30 mmHg, 80%

What happens with the baby's first breath?

Foramen Ovale closes and is now called Fossa Ovalis

Closure of Ductus Arteriosus

What drug with help close PDA--> ligamentum arteriosum?

Indomethacin

What keeps PDA open?

Prostaglandins E1 & E2

SA and AV nodes are usually supplied by what artery?

RCA

Right side dominant circulation (85%)

RCA

Left side dominant circulation (8%)

Left Circumflex Coronary artery (LCX)

Codominant circulation (7%)

LCX and RCA

Which coronary artery is most commonly occluded?

LAD

Coronary blood flow usually peaks when?

Early Diastole

The most posterior part of the heart is the _____; enlargement can cause Dysphagia (due to what?) and Hoarseness (due to what?)

Left Atrium

Compression on esophagus

Compression of left recurrent laryngeal (branch of vagus)

Pericardium consists of 3 layers: from outer to inner

Fibrous pericardium

Parietal layer of serous pericardium

Visceral layer of serous pericardium

Pericardial cavity lies between _____ and _______ layers

Parietal and Visceral layers

cardiac output=

HR x SV

Fick principal

CO= rate of oxygen consumption / (arterial O2 - venous O2)

BP=

CO x TPR

MAP=

2/3 diastolic + 1/3 systolic

Pulse pressure =

systolic - diastolic

Pulse pressure is proportional to what?

Stroke Volume

Pulse pressure is inversely proportional to what?

arterial compliance

SV=

EDV- ESV

During the early stages of exercise, CO is maintained by what?

increase in HR and increase in SV

During the late stages of exercise, CO is maintained by what?

increase in HR only (SV plateaus)

What is shortened with increasing HR that can lead to a decrease CO?

Diastole (less filling time)

Does Pulse Pressue increase or decrease in: Hyperthyroidism

Increase

Does Pulse Pressue increase or decrease in: Aortic regurgitation

Increase

Does Pulse Pressue increase or decrease in: Aortic Stenosis

Decrease

Does Pulse Pressue increase or decrease in: Cariogenic Shock

Decrease

Does Pulse Pressue increase or decrease in: Cardiac Tamponade

decrease

Does Pulse Pressue increase or decrease in: aortic stiffening

Increase

Does Pulse Pressue increase or decrease in: Obstructive sleep apnea (increase sympathetic tone)

increase

Does Pulse Pressue increase or decrease in: exercise

increase

Does Pulse Pressue increase or decrease in: Advanced heart failure (HF)

decrease

Stroke Volume is affected by what 3 things?

What happens to those 3 if there to increase SV?

Contractility (increase)

Afterload (decrease)

Preload (increase)

Does Contractility increase or decrease with:

Catecholamines

Increase

Does Contractility increase or decrease with: Intracellular Calcium

increase

Does Contractility increase or decrease with: Acidosis

Decrease

Does Contractility increase or decrease with: increased extracellular Sodium

Decrease

Does Contractility increase or decrease with: Digitalis

Increase

Does Contractility increase or decrease with: Dilated cardiomyopathy

Decrease

Does Contractility increase or decrease with: Hypoxia (decrease O2)

Decrease

Does Contractility increase or decrease with: Hypercapnia (increase CO2)

Decrease

How does Digitalis work?

blocks Na/K pump--> increase intracellular Na--> decrease Na/Ca exchange--> increase intracellular Ca--> increase contractility

Increase in myocardial oxygen demand is increased by what 4:

Increase in:

Contractility

Preload

After load

HR

What is approximated by EDV; depends on venous tone and circulating blood volume

Preload

What drugs will decrease prEload?

vEnodilators (nitroglycerin)

how does the left ventricle compensate for increased afterload?

thickening (hypertrophy)

What drugs will decrease Afterload?

Vasodilators (hydrAlAzine) (Arterial)

What 2 drugs decrease BOTH afterload and preload?

ACE inhibitors

ARBs

Ejection fraction=

SV/EDV

(EDV-ESV)/EDV

Left ventricular EF is an indicator of what?

Ventricular contractility

Normal EF is what?

> 55%

What happens to EF in systolic HF?

Decreases

What happens to EF in diastolic HF?

Normal

What has the highest total cross sectional area?

Capillaries

What has the lowest flow velocity?

Capillaries

Total resistance in series=

RT= R1 + R2 + R3

Total resistance in parallel=

RT= 1/R1 + 1/R2...

If you remove organs in a parallel arrangement, what happens to TPR and CO?

decrease TPR

Increase CO

What accounts for the most TRP?

Arterioles

What provides the most blood storage capacity?

Veins

Viscosity depends mostly on what?

hematocrit

Viscosity will increase or decrease in multiple myeloma?

Increase

Viscosity will increase or decrease in polycythemia?

Increase

Viscosity will increase or decrease in anemia?

decrease

Viscosity will increase or decrease in Hyperproteinemic states?

Increase

Intersection of curves= operating point of the heart= what?

Venous return and CO are equal

Catecholamines and digoxin do what to Inotropy?

Increase

Uncompensated HF and narcotic overdose does what to Inotropy?

Decrease

Fluid infusion and sympathetic activity does what to venous return?

Increase

Acute hemorrhage and spinal anesthesia does what to venous return?

Decrease

Vasopressors do what to TPR?

increase

Exercise and AV shunt does what to TPR?

Decrease

what is the period of highest O2 consumption?

Isovolumic contraction

where is S1 heart sound heard loudest?

over the mitral area

Where is S2 heart sound heard loudest?

LUSB

What sound is heard in early diastole during rapid ventricular filling?

S3

What sound is heard in late diastole?

S4

where do you hear the S4 sound and in what position?

Apex of heart Left lateral decubitus

What conditions would you hear S3?

increased filling pressures (Mitral regurgitation and HF)

What conditions would you hear S4?

Ventricular noncompliance (hypertrophy)

Can S3 be normal? Can S4 be normal?

Yes, No

a wave=

atrial contraction

c wave =

RV contraction

x descent=

atrial relaxation

v wave=

increased right atrial pressure due to filling against a closed tricuspid valve

y descent=

RA emptying into RV

Systolic heart sounds include: 4

1. Aortic/Pulmonic stenosis

2. Mitral/Tricuspid insufficiency

3. VSD (ventricular septal defect)

4. MVP (mitral valve prolapse)

Diastolic heart sounds include: 2

1. Aortic/Pulmonic Regurgitation

2. Mitral/Tricuspid stenosis